Double Interfacial Layers For Highly Efficient Organic Light-Emitting Devices

The authors report on a highly efficient phosphorescent organic light-emitting device (PHOLED) achieved by introducing nanoscale double interfacial layers, made by ultrathin surfactant and low work-function metal layers. It is shown that double interfacial layers play multiple roles in the enhancement of device performance: increasing electron injection, hole blocking, and reducing surface roughness of electroluminescent layer. With double interfacial layers, a PHOLED has shown efficiency as high as similar to 60 cd/A with a current density of 1.6 mA/cm(2) and a luminance of 1000 cd/m(2) at 6.5 V, which is higher than that of a control device with a single CsF interfacial layer. (c) 2007 American Institute of Physics.